Such luminescent value documents can be e.g. bank notes, checks, coupons or chip cards. Although not restricted thereto, the present invention deals primarily with the check of bank notes. The latter typically contain in the paper or printing ink a feature substance or a mixture of a plurality of feature substances that show luminescence behavior, e.g. that fluoresce or phosphoresce.
There are a number of known systems for checking the authenticity of such value documents. One system is known for example from DE 23 66 274 C2. In this system, to check the authenticity of a bank note, i.e. check specifically whether a fluorescent feature substance is actually present in a bank note to be checked, the latter is irradiated obliquely and the perpendicularly remitted fluorescence radiation detected with spectral resolution using an interference filter. Evaluation is done by comparing the signals from different photocells of the spectrometer.
This system works very reliably in most cases. However, there is a need for a luminescence sensor that has a more compact construction and can still check reliably enough at very low intensities of the luminescence radiation to be detected.